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What is the correct answer?

4

Overall efficiency of a centrifugal pump is the ratio of

A. Energy available at the impeller to the energy supplied to the pump by the prime mover

B. Actual workdone by the pump to the energy supplied to the pump by the prime mover

C. Energy supplied to the pump to the energy available at the impeller

D. Manometric head to the energy supplied by the impeller per kN of water

Correct Answer :

B. Actual workdone by the pump to the energy supplied to the pump by the prime mover


Related Questions

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4

The efficiency of a hydraulic press is given by (where W = Weight lifted by ram, P = Force applied on plunger, A = Area of ram, and a = Area of plunger)

A. (W/p) × (A/a)

B. (p/W) × (a/A)

C. (W/p) × (a/A)

D. (p/W) × (A/a)

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4

By fitting an air vessel to the reciprocating pump, there is always a saving of work done and subsequently saving of power. The saving in case of a double acting reciprocating pump is

A. 39.2 %

B. 48.8 %

C. 84.8 %

D. 88.4 %

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4

Medium specific speed of a pump implies it is

A. Centrifugal pump

B. Mixed flow pump

C. Axial flow pump

D. Any one of the above

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4

The cavitation in reaction turbines is avoided, to a great extent by

A. Installing the turbine below the tail race level

B. Using stainless steel runner of the turbine

C. Providing highly polished blades to the runner

D. All of the above

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4

Which of the following statement is correct as regard to water wheels?

A. They have slow speeds

B. They are suitable even for low water heads

C. They give constant efficiency, even if the discharge is not constant

D. All of the above

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4

Geometric similarity is said to exist between the model and the prototype, if both of them

A. Have identical velocities

B. Are equal in size and shape

C. Are identical in shape, but differ only in size

D. Have identical forces

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4

Which of the following pump is successfully used for lifting water from deep wells?

A. Centrifugal pump

B. Reciprocating pump

C. Jet pump

D. Air lift pump

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4

In centrifugal pumps, maximum efficiency is obtained when the blades are

A. Straight

B. Bent forward

C. Bent backward

D. Radial

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4

A double overhung Pelton wheel has

A. Two jets

B. Two runners

C. Four jets

D. Four runners

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4

The maximum number of jets generally employed in impulse turbine without jet interference is

A. 4

B. 6

C. 8

D. 12

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4

In a reaction turbine, the draft tube is used

A. To run the turbine full

B. To prevent air to enter the turbine

C. To increase the head of water by an amount equal to the height of the runner outlet above the tail race

D. To transport water to downstream

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4

For small discharge at high pressure, following pump is preferred

A. Centrifugal

B. Axial flow

C. Mixed flow

D. Reciprocating

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4

Power required (in watts) to drive a centrifugal pump is (where Hm = Manometric head in metres, w = Specific weight in N/m3, Q = Discharge of the pump in m3/s, and ηo = Overall efficiency of the pump)

A. (w Hm) / (Q × ηo)

B. (w Hm Q) / ηo

C. (w Q) / (Hm × ηo)

D. (w Q ηo) / Hm

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4

The speed ratio in case of Francis turbine varies from

A. 0.15 to 0.3

B. 0.4 to 0.5

C. 0.6 to 0.9

D. 1 to 1.5

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4

The cavitation in a hydraulic machine is mainly due to

A. Low velocity

B. High velocity

C. Low pressure

D. High pressure

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4

The discharge through a reaction turbine ________ with the increase in unit speed.

A. Decreases

B. Increases

C. Remain same

D. None of these

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4

According to fan laws, at constant weight of air or gas, the speed, capacity and pressure vary

A. Directly as the air or gas density

B. Inversely as square root of density

C. Inversely as density

D. As square of density

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4

The discharge through a turbine is

A. Directly proportional to H1/2

B. Inversely proportional to H1/2

C. Directly proportional to H3/2

D. Inversely proportional to H3/2

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4

Which of the following statement is wrong?

A. The reaction turbines are used for low head and high discharge.

B. The angle of taper on draft tube is less than 8°.

C. An impulse turbine is generally fitted slightly above the tail race.

D. A Francis turbine is an impulse turbine.

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4

Axial flow pump is started with its delivery valve

A. Kept fully closed

B. Kept fully open

C. Irrespective of any position

D. Kept 50% open

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4

The unit discharge through the turbine is

A. Q/√H

B. Q/H

C. Q/H3/2

D. Q/H²

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4

Medium specific speed of turbine implies it is

A. Propeller turbine

B. Francis turbine

C. Impulse turbine

D. Any one of the above

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4

In a reciprocating pump, air vessels are used to

A. Smoothen the flow

B. Reduce suction head

C. Increase delivery head

D. Reduce acceleration head

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4

The unit power developed by a turbine is (where P = Power developed by the turbine under a head of water (H).

A. P/ √H

B. P/ H

C. P/ H3/2

D. P/ H²

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4

The specific speed of a turbine is given by the equation

A. N√P / H3/2

B. N√P / H²

C. N√P / H5/4

D. N√P / H3

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4

In a centrifugal pump, the liquid enters the pump

A. At the top

B. At the bottom

C. At the canter

D. From sides

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4

The angle of taper on draft tube is

A. Greater than 15°

B. Greater than 8°

C. Greater than 5°

D. Less than 8°

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4

A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the

A. Kinetic head

B. Velocity head

C. Manometric head

D. Static head

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4

Which of the following is not an impulse turbine?

A. Girad turbine

B. Turgo turbine

C. Pelton wheel

D. Kaplan turbine

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4

An impulse turbine is used for

A. Low head of water

B. High head of water

C. Medium head of water

D. High discharge